1. Field of the Invention
The present invention relates to a process and an apparatus for the production of a semiconductor device, and more particularly to a process which includes a step of vapor growth of Al.sub.2 O.sub.3 on an Si-single crystal of the semiconductor device, and still more particularly to a vapor growth of the Al.sub.2 O.sub.3 on the Si-single crystal.
2. Description of the Prior Art
Various processes for growing Al.sub.2 O.sub.3 on the Si-single crystal have been investigated and reported to employ an Al.sub.2 O.sub.3 layer as the oxide of the semiconductor memory device, or as the protecting layer on the semiconductor surface. In the latter case, the Al.sub.2 O.sub.3 film is used as an alternative to the Si oxide film. For the purpose of attaining the objects of the previous Al.sub.2 O.sub.3 film used as for example, the protecting film, the conventional Al.sub.2 O.sub.3 layer is either amorphous or polycrystalline and not dense. In addition, it is sufficient to form a thin Al.sub.2 O.sub.3 film having a thickness from several hundred to several thousand angstroms in view of the above-mentioned objects of the conventional Al.sub.2 O.sub.3 film.
According to known processes for producing the above-illustrated Al.sub.2 O.sub.3 film, a starting material of the mixed system consisting of an alkyl derivative of aluminum--CO.sub.2 --H.sub.2 or AlCl.sub.3 --CO.sub.2 --H.sub.2 is contacted with an Si-substrate heated to a temperature of from 300 to 1000.degree. C. There processes are inadequate for producing the single-crystal Al.sub.2 O.sub.3 and also disadvantangeous in view of the starting materials as illustrated hereinbelow.
From the aspect of the starting material of the conventional processes, particular problems are evident. The alkyl derivative of Al is dangerous to handle and decomposes a large amount of carbon at a temperature of approximately 300.degree. C. The resulting carbon is then incorporated into the Al.sub.2 O.sub.3 film. The AlCl.sub.3, used as a component of one of the conventional starting materials, is known to have active deliquescence and to absorb water in the reaction system, with the result being that the surface of the Si-substrate is oxidized prior to growth of the Al.sub.2 O.sub.3 film. The Al.sub.2 O.sub.3 film therefore grows without having any relationship to the crystal orientation of the Si-substrate. It is, therefore, almost absolutely impossible to perform the formation of single crystalline Al.sub.2 O.sub.3.
According to the conventional methods, the growth speeds of crystal are approximately several hundred angstroms per minute and are considerably lower than those required for performing the vapor growth of Al.sub.2 O.sub.3 on an industrial scale.